The Effect of Placement Depth of Platform-Switched Implants on Periimplant Cortical Bone Stress

Abstract

The purpose of this study was to evaluate periimplant bone stress distribution for platform-switched implants placed at different depths relative to the bone crest, maintaining the occlusal plane at the same level. Sections of posterior mandibular bone blocks comprising cortical and cancellous bones were simulated in a computer-aided design software. A platform-switched implant was simulated and placed at 1.0 mm supracrestal to 1.8 mm subcrestal positions at 0.1 mm intervals. All bone and implant materials were presumed to be homogenous and isotropic. Conical gold crowns were designed for each model, maintaining the occlusal plane at the same level. Models were analyzed under axial and nonaxial loads. Cortical bone stress increased only slightly from equicrestal to 0.8 mm subcrestal positions, whereas supracrestal and deeper subcrestal positions resulted in higher stress values. Subcrestal positions showed maximum stress concentration away from crestal bone. It can be concluded that shallow subcrestal placement of 2-stage platform-switched implants only slightly increases the stress within the cortical bone.